SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f3c98462d7d4084d1a3201e194771bfd909979c14a772e772e192c7a8af0131' 
  AND token = 'eZLmh1DoioGEhnUZVQhcbwY6/QkDCnEhtHPyDMejw3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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