SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '810038e849a40662543afe6dd211cbde26ba7a93858c43adf2ddf5be10fc9c54' 
  AND token = '7V45Lw2jdw2kL7JYC7sFYRTjMUCWmrfDRSgOiVDhacI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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