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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df9192bd03e3f3aba2799b1585a2d9a91a3d9b5fd1548d2ea538826ed10344a0' 
  AND token = 'n1zhayt+6tN6zbsIbGx/p3VfWUQQdCg+4LcH/8Iu2mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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