SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2b955e889004ca846deb4631f3cceddc1e9baea5abcce4d723be1979643198c' 
  AND token = 'qXMNuyhxrQwNPKdbZYxaGvOcpEl9r89WU5Q2fbOx77k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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