SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fc9efc5a14640e09c9c437d3b8209007d2d04dd2cc6408cbed6c6e48640d9c0' 
  AND token = 'F3wJDMcHFLl7H9lDAMCULwYQeFGnayyVDqsDkPLiXa0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}