SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82b6d4d1aeb7e8235d44896ab4f03459e3b4617ce0c4ed6034b24ec2d5296d37' 
  AND token = '5cf0YrQcvVXKINdPPGx6BF8PwpvnTEd17eVykj2G2/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}