SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be3e8f1b3ab9ca91ddf3a02b74e01e7df9da3fb98f4694b845ce51bcf669a87f' 
  AND token = 'eRA+DP7puH1lA2jLCxQxbXpqGfub/aSqxCbbHZmNSaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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