SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9891f0aa6b021b73126174ed29b4520bc3015b4099571b0f426b81a3dfc2ff7' 
  AND token = '5nUFwLL9ZASjiMAlzvIiIKrz0KtogGmBQRBUrJAtulM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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