SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6e42ec7ef697482e5d642a4f94430bc9f3143ffe0b6cf28da5fdd1d118a448a' 
  AND token = '5XpZFZvcZM9XubAZVZq45+1m6MDv/GRdkllRFuVkHYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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