SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c39809280258af3c7bcadb1c64ef0812c0ebec8a79d931fc0bb4f5e85d54e5d' 
  AND token = '+/ExOVWjLCFvX3+gOhlkIrBGzIKE+j9XeKDo3q3nWm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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