SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38d52972553b5c8a6741648b119a8e707c64baae8c78ff3e2e25db6e2c2cf07c' 
  AND token = 'nQAzOimR4zC3V8qP8Z3zubllkSLMLKqKpzpZ+FmMQAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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