SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '913e887928bacb73b7cb5bb7dcdaacd0f6da18cfebb8870e9f4ba8d8b3be7a70' 
  AND token = 'ls1U71Wmk1RvZcHAbJzuo2kGybeDArPV+7sedyNs2PU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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