SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a534968961e754e8568864adcdd69a36185b38425eb93d1cd9932f32ae615642' 
  AND token = 'iUP295EXeXQlVDG8JaOuuGbr3Cb2zY8TvvqBz0BkAuk=' 
  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"
    }
  }
}