SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4af7c8c09155ed8bff2dda44d7341f3846f9071dbaeeeaa1238a09a790a40fe' 
  AND token = 'I3M+eIOcg3arRXU4iL+ja+Q9t4ZAds29a4ZqhBgwaKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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