SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fe537426d873da9f67bdbd4ab63322e5c42b4a8d4b655d403da777ff5018503' 
  AND token = 'emCBoIROShCJZSToOVOe9DRJcj8jUVVB3epv9yrLSgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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