SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a51fa3ed88de3b93331e0b5ffb4f09fbb549fb2d4322317a5a33598b9312ca6' 
  AND token = '+PqS1qSdMdZNABozyJ6G28+mLHEmRhV3HtXvgIYh5i8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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