SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc54be418fbb5f96cefa673633e3f7e5e62d8bf459de842aa242345924e7c2ba' 
  AND token = 'ytapwNPLYvYbA8RH84jlWF4knFv8sTunSsNFj4lOslI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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