SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a8de9fac001b3449e5ca7d08acffff32dbd45140911cc7af60421787fd3bbf' 
  AND token = 'rNsi6ChaVfldsbwr0bKPZsHemwRej/LdzYbakvpPVa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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