SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e28825faedb7cd3b010f4f1454add922cba7752753a198cb3de698c650f8ab4b' 
  AND token = 'pSdX4Mi8DBgxXwJtg3bWTZZ93No5p+j7IXySo/2xOE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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