SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71e4074b2ac8e34608666f1b9754f12c6187ac2b6845feb0c16101e2d6ae9ddf' 
  AND token = '98JJzTLlEfWdQlZdKoZktJ76mOvSpdnq2n28sO2kZIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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