SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dba6938076b3c412606add8f6c8514a27189fbf1e84b1b2c112f781033214788' 
  AND token = 'KNPaTGtnGCqj5r7ThBbnVC5cJiIJwAt27Hc1N4kUmUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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