SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f142c4372ea691a61040a82220133dff46447e785403b5fc5baf3fb7c288981' 
  AND token = 'P29I2JjplWYEvjV8IoVDS2lEwZAiykvQnfyTv9JOzZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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