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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b86ba28201f27523985003e7256de1f9008487f70d22719617fa50b5f25c8ed' 
  AND token = 't29xQsQTegvYR/DWw2Pv80oNkJO1AvEss01DJ9iXKBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}