SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e79d4ecd6ee25b880fa7e1b28a4ca542b1ab5b1934ad27264533da8d433e1f83' 
  AND token = 'u/FWThCzM7hOBDFrFlqwSS8ipozJ1qTrfr/P6AkT3gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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