SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857bd79b97f54a205a371af8fa318bd44f9d990411cf70c5bee25b2a3dd3c664' 
  AND token = 'nLbJyltonmkrymiyYyA66xHZDB2Mdz+oQ++mZisih48=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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