SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed78c536918f5feb019b5a1dc27c3faf9e5afbd491267f25ea6f6da5264298b8' 
  AND token = 'X4lzUiYSQCF3gFTw8gshtd+qL6pbAqqvpmDNdWquJQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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