SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff98bcfaec054b65eae573f4509e16881b362497f9b6103a943dca7352e1c766' 
  AND token = 'WIEpNzMNcsfphkOexpAdBNyb55vs9aj1bG3TzQlCL58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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