SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '01688d4d0840a5df3d8ed6c366d2f2ab8687a5488ecff9479975b9da73985692' 
  AND token = 'B9m4adm+knvI+gjGLnOITUQjiLTzHfJ0bENwQpqaEwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}