SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff47482bdc7fa73ef1955783a944d76f77a5a54b9504a80b1cf907c3ad80a58b' 
  AND token = 'Q+JvZMYEizwjlhCqwxtmyJI1mdGo98RaG7Jz5YGtM8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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