SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58a20353048dd7fccb6fe15a91dc8c31a634b138f64d95a4427f2e00b8d52a18' 
  AND token = 'lR7FNvzmK7QkmSmjOdryCjzGcglakHdRC63PgzH79ak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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