SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '423de1b0dbbf71d4e256ecbbc4b7124e3ca690d7558440532453becfb90ba199' 
  AND token = 'JlkHSj1y/lW0poI6vybyYV+5KXggSimVxMidPGKoFOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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