SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b6ccaedcd90052ca4ed41c98c35f7fe72f7b0f1ba20ff67f507b27605bd28f0' 
  AND token = '0LqVDBI+xrR7ZKyhaAGaXeJw8z9LvScuaYHhT1lo6YQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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