SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecf2ade432f7c7fd0098b1629995db91d06b354d5bb15b8e8fb8fe12b242f413' 
  AND token = 'RJe09JFqyY/bztt+1i9oJSpScS+BIxtNqdnUUBeMLOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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