SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a00fc8583d014d323c2d86046baa1bc9831319849119ea56bcb844afa400d528' 
  AND token = '5LdZGnGVLS6fk4sBbOzLpdlaXCX+s8FLAwo1X6+etWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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