SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff04af659957fbcf95e803c5bfec735337833bd901e34f0bbf422e304c7f38b' 
  AND token = 'FbQhUEEXkVJejVld/4u2Rae8P7VbcDYAbyuw8sF8nIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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