SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecf7e1ce352015054eb20c19337198e91b89c4bf09d1cd59e7c61dc6c1ba5029' 
  AND token = 'yCB2zDd6yAhiSkHLXiy7KPFjxFnDto7J5Sn3krEr4D8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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