SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a842257d48a0fc5a29150b36b6342b6ad461e1b14a38bb01cdc97e999aab876' 
  AND token = 'NrbJ67/vHMhFbJfMLzHEJ+OJQZJoRdcaI/gFk0pbE1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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