SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e90a9d904830fe130c2c4bd4842b7d6df721f7f6f1cd686d74cf5f956da21c' 
  AND token = 'IqMkNkaJOySBpjPxagmGYsJIVbD+cN9kLHVjrDev4rY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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