SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ba21b65668ff39b1466eb481d75db1e46c653d759af11464d3949388a9c6635' 
  AND token = 'VCQmhlKXPo3/RBpBSVZ5xqQWPzfpiBMlT3o/aF/3Rzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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