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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de50e6449ec5083f9a5dafa751ad7919a0e6619458676a8a861b18b53ca97e97' 
  AND token = 's4HhZ3pqFRjMIN9fAGZj5DAMXLqfHt+lDV/u44d8Ehg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}