SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2875f96119eb38dc3cd762e3c40707c7c23b51831d8325cfe3930a4d12de5626' 
  AND token = 'suJ8+jI0hbS3AZCdFI0mmQVRHTYQTToKRme13U4WJLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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