SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e791b4a5d03677f494d4068e765e77b7663c92b784a98c8e180964e551c18d63' 
  AND token = 'XSgCGugqA2yLQDTvU//5rJaAJ1fviahLKPZCekIRX5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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