SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c349c9fe660d34d49b6f67121e780cb8cdff30db1fbac221f0ccce864d29554' 
  AND token = 'D7ji5BZfinOs5LztnhroYZm/rTzzUSpNlggSWwUnqvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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