SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fa4b6ef5075ffa87f2bfe34c55aec721864e1a35305c8558b7a6fc7e41d2327' 
  AND token = 'vCEBqxREsKsIZPAFFbyo3w2sykWWBvqhsAgTB9q/J+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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