SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c2806d839701ffe0d091276882f79452406e62865e867621118879eadce3252' 
  AND token = 'jUztx+aD05KAGaZMOyIdWYzaZtFYgLkfkHmUYn60Xt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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