SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '667cc568c6f32beace1350817ffaba85fc18a2755b60daa6675d297bc54cc70f' 
  AND token = 'PBoxavKBbhhdT14hcQSAnU61QoEOBvhaPyKmQEg9aO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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