SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0640ad20b0a27bc6ff152bfebbb76e6c26ce3c87edca24937a853113f751b41' 
  AND token = 'CbkvbTm/LB3GQHIzPOx8yznYoXNDNSMuK+7x9VvniWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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