SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f38cc40498c8c725afca3f084b193ebb929ae1a7b36e7a093a67a2f8fe55829c' 
  AND token = 'Ebyblrpcc9pjHix9rPnk5vHIRk1sWES/8EsBroKzQa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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