SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '496fe0d4de70616cd650c5cff646043636d278480d5d59add237367f6d5a613b' 
  AND token = 'B5BaCEBXS1Lg+n3y7DiJx8OtMy/1DbPGfNrwh12A2CA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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