SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e27d5a811d4954bc09b655889ffb145b1239468fb36179aa0cbd757ca820c843' 
  AND token = 'bmuvGgqizmITCG45JywPkXc+V1VJlv10hGZPN2YfHLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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