SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91a0831771c6fbcd269aee023ddd7fdbd81e9ea9471d9ee836a94c56dc69715e' 
  AND token = 'VR6ivpyK4z3TyGQmSHOsmNkY2zByByvNm9H6qSj8rBU=' 
  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"
    }
  }
}