SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50710b8168b10a006ec3f10cbd0cb9ddd336e9cf0c300adc3992ab1b098be790' 
  AND token = 'wUiE7HbrnniQ5RFBz5REGjzRQku56YfWXeBf3mKRYiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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