SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b198e9792d21d6602406ad93e666e9479f4401dae260baffc9bbd4f3f4281d11' 
  AND token = 'SjWfuZSw9FdY0UIWfyZouYZlRNtrukUUO+TfUrlztRc=' 
  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"
    }
  }
}