SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5c2a4ee1aee16fb0629640da7dcd4b50a0d837a7f1829ff9f3159af027fd4bf' 
  AND token = 'PRwKxb404d26M2qDVscUyXter8pGNyRH+869biwzJpI=' 
  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"
    }
  }
}