SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f540c916edb51f67df4f497e406e02a0c91275b245ae472a5d0eaf7a88e281ec' 
  AND token = 'RqUbQ+T8NgGQ+h/aJMDZxCsNFjsgvUWYrsQBF5+JqwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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