SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d2968565b022b4ee7a311f606c5923b72b73866d2df6e0e5d1ecaef7921c491' 
  AND token = 'WXm+3tm2/JX+xzHctQ07varIXmnF3K0CGMlsowJpIJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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