SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f33575d103f0dd622fc70262838c705e02bf993aead854de80cda24880654284' 
  AND token = 'cwTZJjT/hPvmAhLWoBC/dTjoqZLuRV+dUmni3mo/1XQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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