SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb11a5355213b37568468f6f5239a29983e98c19d3e077a4bc0bd9dd6451ca90' 
  AND token = '8t3JppiZhmtES2CKYcygwvBsVPmb++BX5570nBjfjIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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