SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39421115b02f8b024e893e1bce1951344fe53ece87029796b87c017dd36140ec' 
  AND token = 'kScyYCaFdy6dQI7uhxmW3Lcf3799r5kwDaTG7P6oq30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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