SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91fb35d960b43375bf15f205d5631cd1234d773d1f9d7928ebb064f6b294493' 
  AND token = 'USY7migehr6clEqYi22xOhex7KKrlGGIQs3ngFAlGkU=' 
  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"
    }
  }
}