SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4be51649d3c527895c7497b442875fc4bb4d1da09877a16dd481c228ee33322e' 
  AND token = '4yGUzAtLceJKBU+x2/YtoaPVGfeIUKNjQvNE1pQLQh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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