SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bc1d28bad2cc098b1abcad790e8cd84dd9d35f86cfb855ec75ce92d672f454b' 
  AND token = '9IHEbZK97r+bqcnPR5ZeSrTWxIoPRe35/JishCdUVnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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