SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5703e86d06f4f3f68cc2b5e254c04c21bf9297ad9ca9f66028de49d931559e58' 
  AND token = '41SpZMNevGz+UxjgUwSQbAe2RA0mYpsZYl42qgoPrMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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