SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6709d0dae158553f081aff40b560195d95adec6e52b18cbb3b3cfe0f03f5f9af' 
  AND token = 'UDiYWmt+ZPJVmGhmJTG5iQF9twX236G1a5q9+9uEJ/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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