SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90a469fa975a92a9977886fed0ca8ed2f36547053a1e47de17a9b23dee3fd16b' 
  AND token = 'gNdCcchPCdSKkN54lZUXpVMb8pSLPTJqv/xJgItkSM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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