SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f40a13be584f2f39c569cef4312f437902c6ee586853dfd030ec37f79df3c290' 
  AND token = 'tKBkxGBj+npLElDdrxlhkrBHiTSf+qLeKf5xNJuqT08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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