SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c88fd05992033e79c87b1e653c1ad2a1a4c45cdb40fb9d9138314ffb1ba50cfb' 
  AND token = 'h66+AKbCzTVq00I/a6V24OpMjTGJZJ3pu2zAUUJ5B4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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