SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf84e94ee2ae2c4a89b40fe5fef287fdcd4c6ba149135e2899ab5f989bcd43cc' 
  AND token = 'b/z74s5cof6ZjRFdTtfMMHBUVVy695NcXkSq05mwroA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}