SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4debe06cce2db542766d82d2b4c74c2d59775e2008bdf0b07b76e62490be809' 
  AND token = 'nZHBa0Xg3+BVgS7hkSkGTiSSCB3dLE1ihBoSYMs+hsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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